Try Mission4Today. Even if they don't have this particular mission pack, they have bucketloads of missions for IL:1946 and its predecessors. You'll need to register to use the downloads from there, but it's painless and spam free.

Thank you, Tully!
I've been there and registered. And I don't know where to start first. :-)

I just wanted to try some of the official stuff that wasn't included in my copy of 1946. But it seems that Uberdemon keeps all his stuff on his site that is most of the time down.
But I'l try it hard way. I have original Il-2 and first patches. I think that Mission4Today have Demos.
Is it enough to copy those missions in install dir of 1946?
I meant, I don't have to change anything in mission files to make them work in 1946?

MadMate15... Quote "original Il-2 and first patches." Are you talking about "IL-2 Sturmovik" the orginal game and Demos... or the "Il-2 Sturmovik Forgotten Battles/Ace Expansion/Pacific Fighters/1946" as you are asking about the Demo's missions?

If so you can install 1.1 and then the 1.2 patches to bring this game up to date as far as this version of IL-2 is concerned. These can be found at the Mission4Today site along with some Campaign missions.

But there is also these missions put out by UberDemon... Missing Missions From Original IL-2 Sturmovik And Demos Never Included In IL-2 1946 Release (enhanced by me and released with permission from Oleg Maddox. Which is included in a recent UD release for IL-2 1946 4.101m.

I bought IL-2 ages ago and couldn't find time to play it enough. Now I'm starting over again... :-)
I extracted stuff from 1.1 and 1.2 update, Demos, and coop from original that UberDemon stated was missing from 1946 pack.
I didn't test it yet, but I will in next few days.

A further note, missions for the original IL2:Sturmovik game from 2001 will (mostly) work fine in IL2 Forgotten Battles/Ace Expansion/Pacific Fighters (added on to FB/AEP)/1946. As long as the planes, ground objects and maps from the original mission exist in the version you're playing the mission will load without errors. There's a couple that may give difficulty playing if the mission designer has placed certain aircraft away from airfields for a "field" start, but other than that they all should play more or less as intended.